1. Division of Occupational and Environmental Medicine, University of California, San Francisco San Francisco California USA
2. Department of Otolaryngology ‐ Head and Neck Surgery, Ohio State University Columbus Ohio USA
3. Department of Otolaryngology ‐ Head and Neck Surgery, University of California, San Francisco San Francisco California USA
4. Department of Otolaryngology ‐ Head and Neck Surgery, University of Washington & Seattle Veterans Administration Medical Center Seattle Washington USA